The following terms may be used throughout the descriptions presented herein and should generally be given the following meanings unless contradicted or elaborated upon by other descriptions set forth herein.
“Wheel” refers to a generally cylindrical, typically metallic, disc-like mechanical support for supporting a typically pneumatic tire and mounting to a vehicle axle. A wheel has two axially spaced-apart flanges (or annular lips), each flange adapted to securely receive a respective one of the two beads of the mounted tire.
“Tire” is a laminated mechanical device of generally toroidal shape (usually an open-torus) having two beads, two sidewalls and a treaded surface, made of rubber, chemicals, fabric and steel or other materials, and typically inflated with air under pressure. A tire is mounted in the rim bed of a rim.
“Sidewall” of a tire refers to a portion of the tire between the treaded surface and the bead.
The term ‘rim’ refers to the part of a wheel that is made of metal, in particular aluminum, steel, or other alloy, and to which a pneumatic tire, usually made of rubber, is attached. The rim includes a peripherally extending rim bed to which the tire is attached, and a wheel disc portion within the peripherally extending rim bed. That wheel disc portion may have apertures or no aperture at all. The wheel disc may also be formed from spokes.
“Wheel assembly” generally refers to a tire, a combination of a rim and a tire attached thereto, or a wheel.
This disclosure presents non-contact methods and systems for determining a condition of a tire and/or wheel assembly. The tire is fundamentally a rotational axis and a treaded surface disposed between two sidewalls. A non-contact measurement system is used to obtain and determine geometrical parameters of the tire and/or wheel assembly. An exemplary system includes an emitter source for emitting radiation signals towards the tire. A detector is provided for receiving signals reflected from the tire in response to the emitted radiation signals. The reflected signals are fed to a data processing system, such as a computer to determine conditions of the tire/wheel assembly. The data processing system obtains geometrical information, such as height or depth relative to a reference baseline, of a plurality points on the tire, of a plurality points on the tire/wheel assembly is obtained based on the signals received from the detector. According to one embodiment, the plurality of points are on a path extending in a direction from one of the sidewalls to the other. This path may be parallel to the rotational axis of the tire. Based on the height information obtained by the data processing system, a cross-sectional profile of the tire may be created.
In order to determine the condition of the tire, wear conditions of different portions of the tire are compared with each other, to determine whether the tire has uneven wear, and whether the tire has been operated over-inflated or under-inflated. In one aspect, a wear condition comparison is made between points located on one side of a centerline of the circumferential surface of the tire (mostly includes the treaded surface), with points on the other side of the centerline. If a significant difference exists, it is determined that the tire has uneven wear.
According to another embodiment, a wear condition comparison is made between points inside a region extending from the centerline of the circumferential surface towards the sidewalls for a prescribed distance, and points outside the region. For example, this region may be a belt-shape area along the circumferential centerline of the tire. If tire wear in the region is more severe than points outside this region, it is determined that the tire has been operated or run over-inflated. Otherwise, the tire has been operated or run under-inflated. According to still another embodiment, a comparison is made between adjacent tread blocks to determine existence of a sawtooth pattern. If the height of a tread block is significantly lower than the height of the adjacent tread block, it is indicated that the tire has a sawtooth pattern.
The condition of the tire may be determined by generating a surface profile showing respective heights or depths on the surface of the tire. For example, the surface of the tire can be scanned by rotating the wheel assembly to which the tire is attached for 360 degrees. During the rotation, the emitter source continuously emits radiations onto the wheel assembly, and the detector continuously obtains signals reflected from the tire/wheel assembly. A surface profile showing the complete circumferential surface is created. The height/depth information may be shown on a screen using different colors, such that a height distribution on the tire surface is easily observable. The profile may further include height information of the sidewalls. Thus, a bulge on the sidewalls can be determined or observed based on the established surface profile of the tire.
A tire match condition can also be determined by further establishing a profile of a rim to which the tire is attached, by using non-contact measurement systems. Geometrical parameters of a plurality of points located on the treaded surface of the tire and the rim are obtained. For example, the width of the tire and the width of the rim are determined and compared with each other. If a difference between the width of the rim and the width of the tire exceeds a threshold, it is indicated that the tire and the wheel do not match well. According to another embodiment, geometrical parameters of at least one of the sidewalls and the rim are generated. An angle between the one of the sidewalls and the rim is determined. If the absolute value of the angle exceeds a threshold, it is indicated that the tire and the wheel do not match well.
Still other advantages of the presently disclosed methods and systems will become readily apparent from the following detailed description, simply by way of illustration of the invention and not limitation. As will be realized, examples illustrated herein are capable of other and different embodiments, and their several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawing and description are to be regarded as illustrative in nature, and not as restrictive.